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81.
82.
OBJECTIVE: To determine prevalences of heartworm exposure (ie, positive heartworm antibody test results) and heartworm infection (ie, positive heartworm antigen test results or identification of mature heartworms at necropsy) among nondomestic cats housed in an area in rural North Carolina where Dirofilaria immitis is known to be endemic and among nondomestic cats housed in areas with a low prevalence of dirofilariasis or in an area considered to be free from heartworms. DESIGN: Cross-sectional prevalence survey. ANIMALS: 97 nondomestic cats in North Carolina (study population) and 29 nondomestic cats in Colorado; Queensland, Australia; or Auckland, New Zealand (control population). PROCEDURE: Results of serologic tests and postmortem examinations were reviewed. RESULTS: Results of heartworm antibody tests were positive for 57 of 75 (76%) study cats and 1 of 29 (3%) control cats. Male study cats had a significantly higher risk of heartworm exposure than did female study cats (relative risk, 1.3). Results of heartworm antigen tests were negative for all 47 study cats and 16 control cats that were tested. Postmortem examinations were performed on 21 study cats, and 1 (5%) was found to be infected with heartworms. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that nondomestic cats housed outdoors in the southeastern United States are at risk for heartworm exposure and infection, with male cats having a greater risk of exposure than female cats.  相似文献   
83.
抗旱保水剂在紫花苜蓿种植中应用的试验报告   总被引:5,自引:0,他引:5  
用抗旱保水剂对土壤和紫花苜蓿种子处理后,进行种植试验。结果表明,使用抗旱保水剂出苗每平方米较对照地增加24.25株,存苗增加35.62株,苗高平均增加0.32cm,根长平均增长0.69cm,鲜草每平方增加0.41kg。  相似文献   
84.
SUMMARY: The productivity of Merino ewes treated with ivermectin and a controlled-release capsule containing albendazole was compared with untreated ewes grazing the same pastures on each of 3 farms. Treated breeding ewes had significantly increased greasy fleece weights (GFW, 6.5% and 7.1%) compared with untreated breeding ewes, on 2 of 3 farms but treatment caused no significant increase in the GFW of non-breeding ewes. Other benefits of treatment on all farms were a significant increase in body weight gain (from 1.7 to 3.7 kg) and a significant decrease in the weight of dag removed at crutching (from 42 to 622 g). These benefits occurred despite the presence on each farm of worms resistant to benzimidazoles. One disadvantage of treatment was an increase in mean fibre diameter of wool from treated ewes of from 0.12 to 0.41 μm. This increase reduces the value of the wool. Partial budgets indicated a net loss of from 8 to 62 cents per ewe for treatment. However, potential benefits such as increased growth rate and wool production from lambs of treated ewes were not included in the analysis. On one farm ewes were classified as ‘susceptible’ to severe dag if they had a dag score ≥ 4 at the time of capsule treatment. Ewes classified as ‘susceptible’ were about 7 times more likely to develop severe dag than were other ewes. There was no significant difference between the GFW of untreated ‘susceptible’ ewes and untreated ewes not classified as ‘susceptible’. Additionally, the response of GFW to treatment was no different to the response seen in ewes that were not classified as ‘susceptible’. The direct cost of diarrhoea and dag formation in Merino ewes was estimated to be 18, 30, 53, 86, 98 and 145 cents per head for ewes with a dag score of 0, 1, 2, 3, 4 and 5, respectively. This cost did not include potential benefits from reduced risk of breech strike, or intangible benefits associated with the improved welfare of sheep.  相似文献   
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Although the acute death syndrome in feline heartworm disease is widely recognized, its pathogenesis remains a mystery. The most widely held hypothesis is that an acute anaphylactic reaction, perhaps precipitated by the death of the parasite, is the underlying cause. This study investigated the role of the physical form of antigen (Ag) in the ensuing reaction when Dirofilaria immitis-sensitized cats are challenged by intravenous (IV) administration of heartworm Ag. Healthy D. immitis-naive cats (n = 23) were sensitized using subcutaneous injections of adjuvanted D. immitis Ag administered weekly for 6 weeks. After sensitization, cats (n = 20) were anaesthetized and challenged with IV D. immitis Ag in various forms or with IV sterile 0.9% saline (n = 3). Systolic blood pressure, respiratory rate, degree of dyspnea, blood oxygen saturation, and heart rate were measured immediately before and at 10-15 min intervals after challenge until terminal apnea occurred or until euthanasia at 140 min after challenge. Blood samples were collected for complete blood count and measurements of serum serotonin immediately before and at 10, 20, and 35 min after challenge. Clinical observations were recorded as they occurred, or at 10-15 minute intervals, whichever was the more frequent. The most severe post-challenge reactions occurred in cats challenged with Ag from dead worms, live worms, and 20 ng/mL Ag. Dyspnea increased significantly after challenge in all three groups (p < 0.001; p = 0.04, and p = 0.002, respectively), and blood oxygen saturation dropped post-challenge in the Dead Worm (p < 0.001) and the 20 ng/mL Ag (p = 0.002) groups. In the 20 ng/mL Ag group, systolic blood pressure decreased (p <0.05) and respiratory rate increased (p < 0.05) post-challenge. Clinical observations included dyspnea, gastrointestinal signs (retching, defecation, or flatulence), urination, and less commonly, hemorrhage from the nostrils or anus, or cutaneous swelling (general or specifically facial). The 20 ng/mL Ag group had the highest rate of clinical signs, followed by the Dead Worm group. The most common and reliable hematologic change associated with severe clinical effects of D. immitis Ag challenge was increased hematocrit, which was statistically higher after challenge than at baseline in the Dead Worm group (p = 0.012). The model demonstrated that the physical form of heartworm Ag used for IV challenge in D. immitis-sensitized cats is an important factor for determining the characteristics of the post-challenge reaction, and the amount of exposed internal filarial Ag presented to the feline immune system may influence the severity of the response to challenge.  相似文献   
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88.
AIMS: To investigate the production responses and cost-benefit of administering a controlled-release anthelmintic capsule (CRC) to pregnant yearling ewes prior to lambing.

METHODS: Yearling ewes from two commercial sheep flocks (A, n=489; B, n=248) in the North Island of New Zealand were enrolled in the study. Prior to lambing, CRC containing albendazole and abamectin were administered to half the ewes while the other half remained untreated. Ewe liveweights and body condition scores were measured prior to lambing, at weaning and, for Flock B, prior to subsequent mating. Lambs were matched to dams shortly after birth and the weight and number of lamb weaned per ewe were determined. A cost-benefit analysis was undertaken for Flock B considering the increased weight of lamb weaned per ewe, and the weight of ewes at the next mating and the benefit in terms of lambs born.

RESULTS: The mean weight at weaning of treated ewes was greater for treated than untreated ewes by 2.76 (95% CI 0.64–4.88)?kg in Flock A (p<0.001) and 2.35 (95% CI ?0.41–5.12)?kg in Flock B (p=0.003); the weight of lamb weaned per ewe was greater for treated than untreated ewes by 1.43 (95% CI ?0.71 to –3.49)?kg in Flock A (p=0.041) and 3.97 (95% CI 1.59–6.37)?kg in Flock B (p<0.001), and ewe liveweight prior to subsequent mating was greater for treated than untreated ewes in Flock B by 4.60 (95% CI 3.6–5.6)?kg (p<0.001). There was no difference in the percentage of lambs reared to weaning between treated and untreated ewes in either flock (p>0.8). The overall cost-benefit of treatment for Flock B was NZ$9.44 per treated ewe.

CONCLUSIONS AND CLINICAL RELEVANCE: Pre-lambing CRC administration to yearling ewes resulted in increased ewe weaning weights and weight of lamb weaned in both the flocks studied. There was an economic benefit in the one flock where this was assessed.  相似文献   

89.
Feline heartworm disease is caused by the filarial nematode Dirofilaria immitis, and is transmitted by mosquitoes in heartworm-endemic areas worldwide. While dogs are the definitive hosts for this parasite, cats can also be infected, and the overall prevalence in cats is between 5% and 10% of that in dogs in any given area. The spectrum of feline presentations varies from asymptomatic infections to chronic respiratory signs, sometimes accompanied by chronic vomiting to acute death with no premonitory signs. Ante-mortem diagnosis can be challenging and relies on a combination of tests, including antigen and antibody serology, thoracic radiography and echocardiography. As treatment with heartworm adulticidal drugs can be life-threatening and heartworm infection in cats is often self-limiting, infected cats are frequently managed with supportive treatment (corticosteroids, bronchodilators, and anti-emetics). Surgical removal of filariae using extraction devices may be considered in some acute cases where immediate curative treatment is necessary, but filarial breakage during the procedure may result in an acute fatal shock-like reaction. Necropsy findings are mainly pulmonary and include muscular hypertrophy of the pulmonary arteries and arterioles on histopathology. A number of safe and effective macrocytic lactone drugs are available for prophylaxis in cats. These drugs can kill a range of larval and adult life-cycle stage heartworms, which may be advantageous in cases of owner compliance failure or when heartworm infection status is undetermined at the time prophylaxis is commenced. An index of suspicion for feline heartworm disease is warranted in unprotected cats with respiratory signs, and perhaps chronic vomiting, in areas where canine heartworm disease is endemic. Many cats, once diagnosed and with appropriate supportive care and monitoring, will resolve their infection and be free of clinical signs.  相似文献   
90.
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